Follow a standard imaging protocol for this examination. A complete evaluation includes spectral Doppler analysis of all accessible portions of the major intracranial arteries. Velocities can be measured by automatic tracing or manual cursor placement. Bilateral evaluations are essential for a complete evaluation.

Spectral Doppler waveforms include the following vessels and approaches (without angle correction). Waveforms are obtained at 2-5mm increments, or walked through each vessel of interest:

• Submandibular Window:
  • Distal cervical internal carotid arteries (ICA)
• Transtemporal Window:
  • Terminal internal carotid arteries (TICA)
  • M1 segment of the middle cerebral arteries (MCA)
    • Should obtain proximal, mid and distal measurements
  • A1 segment of the anterior cerebral arteries (ACA)
  • Anterior communicating artery, if detectable (ACoA)
  • P1 and P2 segments of the posterior cerebral arteries
  • Posterior communicating arteries, if detectable (PCoA)
• Transforamenal/Suboccipital Window:
  • Terminal vertebral arteries (VA)
  • Proximal and distal segments of the basilar artery (BA)
• Orbital Window: (not typically utilized for this exam)
  • Ophthalmic Artery (OA)
  • Carotid siphon

Technical Considerations:

• Time averaged maximum mean (TAMM) flow velocities are used for interpretation
• Mean flow velocities are classified as normal, conditional or abnormal
• Diagnosis applies specifically to the internal carotid and middle cerebral arteries
• TCD detection of abnormal mean flow velocities on two separate exams determines the need for blood transfusions to reduce stroke risk
• Abnormal studies should be verified with a second exam, preferably within a one to two week period
• Conditional exams should be repeated within 3-6 months to document progression
• In young children, the temporal bone is easy to penetrate. It may be possible to complete most of the exam from one side. This must be documented to prevent confusion and misdiagnosis of flow direction or velocity.
• The STOP Trial did not include the orbital exam; however, if a temporal window cannot be identified, the orbital exam may be useful, as it provides access to the carotid siphon (power must be decreased for this approach).